Question: How many significant figures does $0.253971000$ have?
Identify the non-zero digits and any zeros between them. These are all significant. $0.{253971}000$ Leading zeros are not significant. $\color{orange}{0.}{253971}000$ Since there is a decimal, trailing zeros are significant. $\color{orange}{0.}{253971000}$ Counting all the significant digits gives us 9.